There is a big disparity between Botanist marks rewards and other DoL rewards from leves. When I do my miners leves from Uldah, I get between 1200 to 1800 marks from 1 Nophica Wells leve (rank 30.) When I did a Camp Bloodshore fishing leve (rank 20) I got 1100 marks. I just did my Humblehearth botanist leve (rank 30) and I got 900 marks. Also, there are times after a leve reset when there are no leves that give marks.